An ultra-strong and ductile crystalline-amorphous nanostructured surface layer on TiZrHfTaNb0.2 high-entropy alloy by laser surface processing

•A crystalline-amorphous nanostructured top surface layer is developed on a high-entropy alloy by laser surface processing.•The phase decomposition-mediated mechanisms forming the crystalline-amorphous nanostructured surface layer are uncovered.•Localized micro-pillar compression tests on surface layer shows an ultrahigh yield strength and a good compression strain .•The co-deformation cooperative actions include dislocation activities in nanograins but crystallization in amorphous GBs.•The co-deformation cooperative effects subsequently lead to the grain coarsening via GB-mediated plasticity.